Quote Originally Posted by shermur View Post
When I worked in piece factories (Key Industries and Levi Strauss) the same protocol counts for home machines. When a needle gets used (depending on the thickness of fabric and what size machine needle you are using); you replace the needle when you hear the "punching" sound or when you check for small "burrs" at the end of the needle....
Since yo mention that "punching" sound...do you know... I usually use cotton for everything, but use 50/50 polyester/cotton broadcloth for linings. Yesterday I was sewing the quilt part and the sound was not there. Then I switch to make the lining (I was making a cover for my sewing machine) and I started sewing the lining together and that loud punching sound started and lasted the whole time working with the poly blend. I then sewed the two pieces together, and....no sound..

Do you know anything about polyester being harder on needles or why that sound on poly but not cotton? I assume it probably has something to do with the weave and some poly in there, but that is just a guess.